This application under 35 U.S.C. Section 371 of International Application Number PCT/FR99/02377 filed on Oct. 05, 1999.
The present invention relates to novel coating compositions, in particular paint compositions. These compositions can be used in various applications, such as water paints, roughcasts, transparent coatings, impregnations or semi-thick coatings (STC).
The prior art does not indicate a coating composition capable of correctly and satisfactorily crosslinking by condensation into an elastomer or a crosslinked material which confers, on the final application, for example in the form of a paint, a high wet abrasion resistance (WAR), a satisfactory impermeability to water and a satisfactory permeability to water vapor. In addition, the prior art does not indicate coating compositions which have a high and enduring stability on storage (maintenance of the content of VOCs or of alcohols produced in situ below a breakdown threshold of the composition).
One of the essential objectives of the present invention is thus to provide a novel coating composition which confers, on the final application, efficient water-repellency, that is to say high wet abrasion resistance (WAR), satisfactory impermeability to water, satisfactory permeability to water vapor and a satisfactory pearling effect. In addition, the novel coating composition has a high and enduring stability on storage.
More specifically, the novel coating composition developed, which forms the subject-matter of the present invention, comprises:
(A) 3 to 30 parts (solids content at approximately 50% by weight) of a latex composed of particles of organic (co)polymers exhibiting a glass transition temperature of between xe2x88x9220xc2x0 C. and 50xc2x0 C.,
(B) 0.05 to 5 parts (solids content at approximately 65% by weight) of an epoxyfunctionalized polyorganosiloxane emulsion,
(C) and 100 (solids content at approximately 75% by weight) parts of inorganic fillers.
In the context of the invention, the parts (A) and (B) form what is known as the binder of the coating composition.
The latex used in the context of the composition according to the invention is prepared from polymerizable monomers (1) chosen from styrene, butadiene, acrylic esters and/or vinyl nitrites.
The term xe2x80x9cacrylic estersxe2x80x9d denotes esters of acrylic acid and of methacrylic acid with C1-C12, preferably C1-C8, alkanols, such as methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate or isobutyl methacrylate.
The vinyl nitriles include those having from 3 to 12 carbon atoms, in particular acrylonitrile and methacrylonitrile.
Styrene can be replaced, in all or in part, by amethylstyrene or vinyltoluene.
Other ethylenically unsaturated monomers (2) which can be polymerized with the above monomers (1), the amount of which can range up to 40% by weight of the total of the monomers, can also be used for the preparation of the latex of the composition according to the invention. Mention may be made of:
(a) carboxylic acid vinyl esters, such as vinyl acetate, vinyl versatate or vinyl propionate,
(b) unsaturated ethylenic mono- and dicarboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid, and monoalkyl esters of the dicarboxylic acids of the type mentioned with alkanols preferably having 1 to 4 carbon atoms and their N-substituted derivatives,
(c) amides of unsaturated carboxylic acids, such as acrylamide, methacrylamide, N-methalolacrylamide or -methacrylamide,
(d) ethylenic monomers comprising a sulfonic acid group and its alkali metal or ammonium salts, for example vinylsulfonic acid, vinylbenzenesulfonic acid, a-acrylamido-methylpropanesulfonic acid or 2-sulfoethylene methacrylate,
(e) ethylenically unsaturated monomers comprising a secondary, tertiary or quaternary amino group or a heterocyclic group comprising nitrogen, for example vinylpyridines, vinylimidazole, aminoalkyl (meth)acrylates and aminoalkyl(meth)acrylamides, such as dimethylaminoethyl acrylate or methacrylate, di-tert-butylaminoethyl acrylate or methacrylate, dimethylaminomethylacrylamide or -methacrylamide, as well as zwitterionic monomers, such as sulfopropyl(dimethyl)aminopropyl acrylate, and the like,
(f) esters of (meth)acrylic acids with alkanediols preferably comprising 2-8 carbon atoms, such as glycol mono(meth)acrylate, hydroxypropyl mono(meth)acrylate or 1,4-butanediol mono(meth)acrylate, and monomers comprising two polymerizable double bonds, such as ethylene glycol dimethacrylate.
According to a preferred alternative form for the choice of the latex, the latter comprises, by weight:
25-90% and preferably 45-75% of styrene and/or acrylonitrile,
75-10% and preferably 55-25% of butadiene and/or acrylates,
0-20% and preferably 1-10% of unsaturated carboxylic acid,
and 0-40% and preferably 0-15% of other unsaturated ethylenic monomers.
The polymerization of the latex is carried out in a way known per se in an aqueous emulsion of the polymerizable monomers in the presence of at least one radical initiator and preferably of a transfer agent, for example of the mercaptan type, with a concentration of monomers in the reaction medium generally of between 20 and 60% by weight.
The polymerization can be carried out continuously, batchwise or semicontinuously with introduction of a portion of the monomers continuously and can be of the xe2x80x9cseededxe2x80x9d or xe2x80x9cincrementalxe2x80x9d type according to any alternative form known for the production of particles with a homogeneous and heterogeneous structure.
For the preparation of the latex, reference will be made, as non-limiting example, to the procedures disclosed in patent EP 599 676 on behalf of the present applicant company.
Mention may be made, as examples of inorganic fillers of the composition according to the invention, of milled quartz, kaolin, fumed silica, precipitated silica, calcium carbonate, barium sulfate, titanium oxide, talc, hydrated alumina, bentonite, calcium sulfoaluminate, and the like.
The epoxyfunctionalized polyorganosiloxanes of the composition according to the invention are linear and/or cyclic. Identical or different polyorganosiloxanes can be used within the same coating composition. These polyorganosiloxanes are composed of units of formula (I) and are terminated by units of formula (II) and/or are composed of units of formula (I) which are represented below: 
in which:
the R1 symbols are alike or different and represent:
a linear or branched alkyl radical comprising from 1 to 8 carbon atoms, the alkyl radicals preferably being methyl, ethyl, propyl and octyl,
a cycloalkyl radical comprising between 5 and 8 cyclic carbon atoms which is optionally substituted,
an aryl radical comprising between 6 and 12 carbon atoms which can be substituted, preferably phenyl or dichlorophenyl,
an aralkyl part having an alkyl part comprising between 5 and 14 carbon atoms and an aryl part comprising between 6 and 12 carbon atoms which is optionally substituted on the aryl part by halogens, alkyls and/or alkoxyls comprising 1 to 3 carbon atoms,
the Yxe2x80x2 symbols are alike or different and represent:
the R1 group,
and/or an epoxyfunctional group, connected to the silicon of the polyorganosiloxane via a divalent radical comprising from 2 to 20 carbon atoms which can comprise at least one heteroatom, preferably oxygen,
and at least one of the Yxe2x80x2 symbols representing an epoxyfunctional group.
The linear polyorganosiloxanes can be oils with a dynamic viscosity at 25xc2x0 C. of the order of 10 to 10 000 mPaxc2x7s at 25xc2x0 C., generally of the order of 50 to 5000 mPaxc2x7s at 25xc2x0 C. and more preferably still of 100 to 600 mPaxc2x7s at 25xc2x0 C., or gums exhibiting a molecular mass of the order of 1000000.
When cyclic polyorganosiloxanes are involved, these are composed of units (II) which can be, for example, of the dialkylsiloxy or alkylarylsiloxy type. These cyclic polyorganosiloxanes exhibit a viscosity of the order of 1 to 5000 mPaxc2x7s.
Mention may be made, as examples of divalent radicals connecting an organofunctional group of the epoxy type, of those included in the following formulae: 
The dynamic viscosity at 25xc2x0 C. of all the silicones considered in the present description can be measured using a Brookfield viscometer according to the AFNOR standard NFT 76 102 of February 1972.
The production of such functionalized polyorganosiloxanes is entirely within the scope of a person skilled in the art of the chemistry of silicones.
According to an advantageous alternative form, the composition of the invention comprises from 5 to 100 organofunctional groups per 100 Si units and preferably from 20 to 40, which makes it possible to obtain an excellent compromise between the stability of the composition and its water repellency.
In addition to the three main constituents of the coating composition of the invention, the latter can comprise 0.1 to 10 (dry) parts of additives, such as antifoamting agent(s), biocide(s), surfactant(s), rheological agent(s), coalescence agent(s), dispersing agent(s), neutralizing agent(s) and thickening agent(s).
For the preparation of the coating composition, the various constituents are mixed in a way known per se.
The coating composition according to the invention can be applied according to the usual techniques. By way of example, it can be applied to surfaces by any suitable means, such as brush, sprayer, and the like. The surfaces to which the coating composition according to the invention can be applied are various in nature: for example, metal, such as aluminum, wood, cement or brick, with or without precoating with an adhesion primer.